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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

1461 results found.

  1. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  2. LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
  3. IceCube-250203A - IceCube observation of a high-energy neutrino candidate track-like event
  4. EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
  5. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  6. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  7. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  8. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  9. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  10. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  11. IceCube Alert 250102.58: Global MASTER-Net observations report
  12. IceCube-250102A - IceCube observation of a high-energy neutrino candidate track-like event
  13. IceCube-250101A - IceCube observation of a high-energy neutrino candidate track-like event
  14. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  15. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  16. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  17. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  18. IceCube-241224A - IceCube observation of a high-energy neutrino candidate track-like event
  19. IceCube Alert 241224.30: Global MASTER-Net observations report
  20. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  21. IceCube-241127A: Upper limits from a search for additional neutrino events in IceCube
  22. Swift-XRT observations of IceCube -241127A
  23. Fermi-LAT gamma-ray observations of IceCube-241127A
  24. IceCube Alert 241127.59: Global MASTER-Net observations report
  25. IceCube-241127A: IceCube observation of a high-energy neutrino candidate track-like event
  26. LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
  27. Updates to IceCube realtime alert system for muon tracks
  28. IceCube-Cascade 241116A: Upper limits from a search for additional neutrino events in IceCube
  29. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  30. Fermi-LAT gamma-ray observations of IceCube-241113A
  31. IceCube-241113A - IceCube observation of a high-energy neutrino candidate track-like event
  32. IceCube Alert 241113.02: Global MASTER-Net observations report
  33. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  34. LIGO/Virgo/KAGRA S241106ba: 1 counterpart neutrino candidate event from an IceCube neutrino search
  35. LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
  36. IceCube-Cascade 241019A: Upper limits from a search for additional neutrino events in IceCube
  37. IceCube alert 139977_2910365 retraction
  38. IceCube Alert 241016.04: Global MASTER-Net observations report
  39. IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
  40. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  41. IceCube-241006A: No candidates from the Zwicky Transient Facility
  42. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  43. IceCube Alert 241006.94: Global MASTER-Net observations report
  44. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  45. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  46. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  47. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  48. LIGO/Virgo/KAGRA S240930df: 1 counterpart neutrino candidate event from an IceCube neutrino search
  49. AMON NuEM 240926A: Swift XRT Follow-up
  50. IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event
  51. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240926A
  52. GRB 240825A: Upper limits from a neutrino search with IceCube
  53. IceCube-240721A: AT2023qqp and AT2024pge likely unrelated
  54. IceCube-240808A: Upper limits from a search for additional neutrino events in IceCube
  55. Fermi-LAT gamma-ray observations of IceCube-240808A
  56. IceCube Alert 240808.27: Global MASTER-Net observations report
  57. IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
  58. IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
  59. Fermi-LAT gamma-ray observations of IceCube-240725A
  60. IceCube Alert 240725.22: Global MASTER-Net observations report
  61. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  62. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  63. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  64. Fermi-LAT gamma-ray observations of IceCube-240721A
  65. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  66. IceCube Alert 240721.68: Global MASTER-Net observations report
  67. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  68. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  69. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  70. IceCube-Cascade 240626A: Upper limits from a search for additional neutrino events in IceCube
  71. IceCube-Cascade 240518A: Upper limits from a search for additional neutrino events in IceCube
  72. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  73. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  74. Fermi-LAT gamma-ray observations of IceCube-240424A
  75. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  76. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  77. IceCube Alert 240424.08: Global MASTER-Net observations report
  78. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  79. Fermi-LAT gamma-ray observations of IceCube-240419A
  80. IceCube Alert 240419.98: Global MASTER-Net observations report
  81. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  82. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  83. IceCube-Cascade 240416A: Upper limits from a search for additional neutrino events in IceCube
  84. IceCube-240412A: Upper limits from a search for additional neutrino events in IceCube
  85. Fermi-LAT gamma-ray observations of IceCube-240412A
  86. IceCube Alert 240412.23: Global MASTER-Net observations report
  87. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  88. IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
  89. Fermi-LAT gamma-ray observations of IceCube-240327B
  90. Fermi-LAT gamma-ray observations of IceCube-240327A
  91. IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
  92. IceCube-240327B: Upper limits from a search for additional neutrino events in IceCube
  93. IceCube-240327A: Upper limits from a search for additional neutrino events in IceCube
  94. IceCube-240327B: No candidates from the Zwicky Transient Facility
  95. IceCube Alert 240327.68: Global MASTER-Net observations report
  96. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  97. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  98. Fermi-LAT gamma-ray observations of IceCube-240307A
  99. IceCube-240307A: Upper limits from a search for additional neutrino events in IceCube
  100. IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event

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